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Rollup merge of #133330 - RalfJung:close, r=the8472

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library: update comment around close()

r? `@the8472`
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许杰友 Jieyou Xu (Joe) 2024-11-22 20:32:38 +08:00 committed by GitHub
commit bbc4cbe3e2
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1 changed files with 11 additions and 10 deletions
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library/std/src/os/fd/owned.rs
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@ -173,16 +173,17 @@ impl Drop for OwnedFd {
#[inline]
fn drop(&mut self) {
unsafe {
// Note that errors are ignored when closing a file descriptor. The
// reason for this is that if an error occurs we don't actually know if
// the file descriptor was closed or not, and if we retried (for
// something like EINTR), we might close another valid file descriptor
// opened after we closed ours.
// However, this is usually justified, as some of the major Unices
// do make sure to always close the FD, even when `close()` is interrupted,
// and the scenario is rare to begin with.
// Helpful link to an epic discussion by POSIX workgroup:
// http://austingroupbugs.net/view.php?id=529
// Note that errors are ignored when closing a file descriptor. According to POSIX 2024,
// we can and indeed should retry `close` on `EINTR`
// (https://pubs.opengroup.org/onlinepubs/9799919799.2024edition/functions/close.html),
// but it is not clear yet how well widely-used implementations are conforming with this
// mandate since older versions of POSIX left the state of the FD after an `EINTR`
// unspecified. Ignoring errors is "fine" because some of the major Unices (in
// particular, Linux) do make sure to always close the FD, even when `close()` is
// interrupted, and the scenario is rare to begin with. If we retried on a
// not-POSIX-compliant implementation, the consequences could be really bad since we may
// close the wrong FD. Helpful link to an epic discussion by POSIX workgroup that led to
// the latest POSIX wording: http://austingroupbugs.net/view.php?id=529
#[cfg(not(target_os = "hermit"))]
{
#[cfg(unix)]